48 



Records of the Indian Museum. 



[Vol. IX 



distinguishable, and the edge of the front is distinct from the 

 edge of the antennular fossse. 



With more material it may hereafter be shown that the pre- 

 sent form is entitled to specific rank, but for the present I prefer 

 to regard it as a variety of P. malaharica. This determination is 

 equivalent to the admission that certain characters, which have 

 been regarded as of value in separating the so-called species of fresh- 

 water crabs, are liable to considerable variation in closely related 

 individuals. It would no doubt be possible, in some cases, to 

 discover slight differences which are more or less constant, among 



Fig. I. — Paratelphusa malabarica, Henderson, d" type, x 3. 



Fig. 2. — Paratelphusa malabarica var. travancorica, nov., cf type, x 3. 



individuals belonging to one of the recognized ' species,' if col- 

 lected from different streams and particularly from those on differ- 

 ent hill ranges, but it may be doubted if any benefit would result 

 from the attempt to name such slightly marked varieties. In the 

 new variety just described, the characters on which it is based 

 cannot, however, be described as slight. 



This Travancore crab also illustrates the difficulty which some- 

 times arises in connection with the assignment of a species to one 

 or other of the so-called subgenera. It cannot be said to show 

 obscure epigastric and postorbital crests, which is one of the out- 



